When using a winch to raise a payload, a winch cable is attached to a motor-driven drum at one end and the payload at the other. The motor is driven to rotate the drum in order to gather up the winch cable on the outer circumference of the drum. In a modern hoist or winch system, a clutch is provided to limit the torque applied to the drum. The clutch comprises input and output friction plates that are biased together into frictional engagement with each other, to allow the transfer of drive from the motor to the drum through the clutch. The biasing of the plates is set to allow the plates to slip relative to each other at a particular maximum torque value suitable for the clutch. The slipping of the plates will disconnect the motor from driving the drum. The clutch therefore prevents an overload from damaging the winch, motor or the structure it is attached to.
When the plates slip relative to each other the dynamic friction between them will generate significant heat. If unchecked, this heat may cause damage to the plates or other internal components of the clutch. This may compromise the lifetime or effectiveness of the clutch/winch system.